Re: [PATCH kmod v5 5/5] libkmod, depmod, modprobe: Make directory for kernel modules configurable

From: Jan Engelhardt <jengelh@inai.de>
To: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: "Michal Suchanek" <msuchanek@suse.de>,
	linux-modules@vger.kernel.org, "Takashi Iwai" <tiwai@suse.com>,
	"Lucas De Marchi" <lucas.de.marchi@gmail.com>,
	"Michal Koutný" <mkoutny@suse.com>,
	"Jiri Slaby" <jslaby@suse.com>,
	"Masahiro Yamada" <masahiroy@kernel.org>,
	"Nathan Chancellor" <nathan@kernel.org>,
	"Nick Desaulniers" <ndesaulniers@google.com>,
	"Nicolas Schier" <nicolas@fjasle.eu>,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH kmod v5 5/5] libkmod, depmod, modprobe: Make directory for kernel modules configurable
Date: Wed, 18 Oct 2023 03:25:19 +0200 (CEST)	[thread overview]
Message-ID: <o6n5s896-ppro-qs00-71q8-3s657s3190s9@vanv.qr> (raw)
In-Reply-To: <e3yow7ih6af2hxzkmjay2oan3jypmo4hda64vxvpfco66ajcew@i3zewn4nbklf>

On Tuesday 2023-10-17 19:50, Lucas De Marchi wrote:
>> +AC_ARG_WITH([module_directory],
>> +        AS_HELP_STRING([--with-module-directory=DIR], [directory in which to
>> look for kernel modules - typically '/lib/modules' or
>> '${prefix}/lib/modules']),
>> +        [], [with_module_directory=/lib/modules])
>> +AC_SUBST([module_directory], [$with_module_directory])
>
> we will probably have "fun" results if we accept a relative path here.

$ ./configure --prefix=/usr --bindir=../bin
configure: error: expected an absolute directory name for --bindir: ../bin

While such check does not exist for --with-module-directory, everyone
has likely been well-trained not to use relative paths. Even if, say,
cmake/meson *could* do it, it just would have never occurred to me to
actually *utilize* it, because it is just too ambiguous and
potentially dangerous.

Just think of all the fun you could have with LD_LIBRARY_PATH=".."